We are fond of saying things are symmetric, but what does that really mean? Intuitively we have a sense of symmetry as a kind of mirroring. Suppose we draw a vertical line through the middle of a ...

Breakthroughs in physics sometimes require an assist from the field of mathematics—and vice versa. In 1912, Albert Einstein, then a 33-year-old theoretical physicist at the Eidgenössische Technische ...